Complete the recursive formula of the arithmetic sequence $20, 26, 32, 38,...$. $a(1)=$
The first term is $20$ and the common difference is $6$. ${+6\,\curvearrowright}$ ${+6\,\curvearrowright}$ ${+6\,\curvearrowright}$ $20,$ $26,$ $32,$ $38,...$ This is the recursive formula of $20, 26, 32, 38,...$ $\begin{cases} a(1)=20 \\\\ a(n)=a(n-1)+6 \end{cases}$